OBD-II reference

All 9.533 generic OBD-II codes, explained in detail.

Causes, inspection steps and sources — a comprehensive DIY archive. Created and maintained with love for the detail. Good luck and have fun!

Powertrain generic / SAE

P01A8

Alternative Fuel Rail/System Pressure - Too Low

Alt fuel rail or system pressure below the expected operating range.

SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number1 / A8

Possible causes

  • Alt fuel pump weak high

Inspection / repair

  • Difficulty: hard
  • DIY: shop recommended
  • Estimated cost: 200–2000 €
  • Estimated time: 1.5–6 h
  • Component: alt fuel pump
  • Component: alt fuel lines
  • Component: regulator
  • MIL / check engine light
  • emissions-relevant
  • drive cycle required
  • limp mode possible

Sources

References

sae:J2012

How to read OBD-II codes

The first letter names the vehicle system, the second digit distinguishes generic from manufacturer-specific, the remaining digits group fault area and number.

PPowertrain: engine, transmission, emissions
BBody: chassis trim, comfort, interior
CChassis: suspension, brakes, steering
UNetwork: CAN, control modules, communication